This invention relates generally to turbine engines and, more particularly, to methods and apparatus for fabricating a fan assembly for use with a turbine engine.
At least some known turbine engines include a fan assembly that channels air to a compressor. Known fan assemblies include a plurality of fan blades that extend radially outward from a rotor shaft. The rotor shaft has an axis of rotation that passes through a center of gravity of the fan assembly. During normal operations, the rotor rotates about the axis of rotation within an orbiting diameter. Generally, the orbiting diameter is configured to be minimized during normal engine operations.
During operation of the engine, a fragment of a fan blade may become separated from the remainder of the blade and/or the blade may become separated from the rotor. This is commonly referred to as a “bladeout”. When such damage occurs, a substantial rotary unbalance load may be created within the damaged fan assembly that may cause the orbiting diameter of the rotor to increase. As a result, the remaining intact fan blades may contact the surrounding fan assembly casing, which, over time, may cause damage to such blades and/or the casing.
At least some known fan assemblies include a filler material that is applied to the fan casing. The filler material facilitates reducing a gap defined between the tips of the fan blades and the fan casing. Known filler materials are typically made from a composite material that erodes when contacted by a fan blade. Accordingly, during a bladeout, at least one fan blade may cause the filler material to erode, such that a sufficient gap is defined between the remaining fan blades and the casing. The increased gap facilitates accommodating the increased orbiting diameter of the rotor. By freely accommodating the orbiting of the rotor, the rotary unbalance forces transmitted to the rest of the engine are reduced. However, at least some known filler materials increase the overall weight of the engine enough that the filler material weight may actually decrease engine efficiency and/or increase costs associated with engine fabrication, assembly, and/or maintenance.